One-step electrochemical modification of carbon nanotubes by ruthenium complexes via new diazonium salts

The synthesis of new diazonium salts of bipyridine or terpyridine ruthenium complexes is described. Introduction of a phenyl spacer between a metal ligand and the N₂⁺ group play a key role to stabilize these compounds. Electrochemical experiments performed first on vitreous carbon present the reduction of diazonium ion to a radical and the electrografting of metal complexes on the carbon surface. The films formed on the electrode surface are stable, adherent and electrochemically active (redox polymers). On the basis of these results, diazonium ruthenium complexes have been electropolymerized on carbon nanotubes bucky papers. In spite of the increase in electrical resistance, the analysis of the electrochemical behavior of the modified nanotubes provides evidence of the typical electrochemical signature of metal complexes grafted on the bucky paper, also confirmed with UV-vis and Raman spectroscopies.